Specifications

Serial Interface
18.3 Requirements made of external units
Only units which have been tested according to EN 60950
(=IEC 950) should be connected to the interface of the cir-
culator.
18.4 Setting the desired set value
If the desired set value is set via the computer, this means:
If the interface connection is interrupted, the circulator
controls the temperature to the last set value entered
via the interface.
After the mains .supply current has been switched off
and on, the circulator controls the temperature to the
last value entered via its keyboard and not the value
given by the computer.
18.5 Watchdog function
A watchdog can be initialised via the interface, in order to
generate an acoustic alarm when no trigger command has
been received via the interface within the set timeout period.
The circulator then continues operation with the most
recently manually set (via the menu function) setpoint tem-
perature as safety temperature. The most recently received
setpoint from the interface
is therewith no longer valid. Thus
the instrument is not switched-off as it would be in the case
of an ordinary disturbance (liquid level,
BATH overtempera-
ture, etc.). The response delay time of the watchdog can be
changed via the interface. The default setting after switch-on
is 20 seconds.
The watchdog (WD) setting is displayed on the menu path
WD-V24: 0/0020/+000015
I I !---current WD remaining response
delay in seconds
1
I---WD response time setpoint in sec.
(0 ... 9999 sec)
I---WD
status (0 inactive,
1 active)
By reference to the WD remaining response delay time
indication, after the watchdog has responded, it is pos-
sible to determine the instant at which communication
failed. This is possible because the residual time is
shown with sign. The value is positive for as long as the
WD has not responded.